Comprehensive Evaluation of Bile Acid Homeostasis in Human Hepatocyte Co-Culture in the Presence of Troglitazone, Pioglitazone, and Acetylsalicylic Acid

Interruption of bile acid (BA) homeostasis has been hypothesized for a variety of liver diseases and for drug-induced liver injury (DILI). Consequently, BA is gaining increasing prominence as a potential biomarker. The objective of this work was to evaluate the effect of troglitazone (TZN, associated with severe DILI), pioglitazone (PZN, rarely associated with DILI), and acetylsalicylic acid (ASA, or aspirin, not associated with DILI) on the in vitro BA homeostasis in hepatocytes co-cultured with nonparenchymal cells by monitoring the disposition of 36 BAs. The cells were supplemented with 2.5 mu M d(4)-cholic acid, d(4)-chenodeoxycholic acid, d(4)-lithocholic acid, d(4)-deoxycholic acid, d(4)-ursodeoxycholic acid, and hyodeoxycholic acid. Concentration-time profiles of BAs were used to determine the area under the curve from the supernatant, lysate, or bile compartments, in the presence or absence of TZN, PZN, or ASA. When applicable, IC50 describing depletion of individual BAs was calculated, or accumulation greater than 200% of dimethyl sulfoxide control was noted. Thiazolidinediones significantly altered the concentration of glycine and sulfate conjugates; however, more BAs were impacted by TZN than with PZN. For commonly shared BAs, TZN exhibited 3- to 13-fold stronger inhibition than PZN. In contrast, no changes were observed with ASA. Modulation of BA disposition by thiazolidinediones and ASA was appropriately differentiated. Particularly for thiazolidinediones, TZN was more potent in interrupting BA homeostasis, and, when also considering its higher dose, may explain differences in their clinical instances of DILI. This is one of the first works which comprehensively evaluated the disposition of primary and secondary BAs along with their metabolites in an in vitro system. Differing degrees of BA homeostasis modulation was observed with various perpetrators associated with varying clinical instances of DILI. These data indicate that in vitro systems such as hepatocyte co-cultures may be a promising tool to gain a detailed insight into how drugs affect BA handling to further probe into the mechanism of DILI related to BA homeostasis.